Box with snap-on closure

ABSTRACT

A closure system with a three-dimensional structure with an opening and a lid for plugging onto the three-dimensional structure in order to close the opening. The lid is bistably deformable between a first state, in which its end wall is curved in the plug-in direction, and a second state, in which the end wall is curved against the plug-in direction. An annular edge section of the lid has a greater outer circumference in the first bistable state than in the second bistable state and forms a clamping fixture of the lid to a wall region of the opening when the edge section is pressed inwards in the first state or outwards against the wall region in the second state. The three-dimensional structure transfers a force from the outside at specified locations that to a snapping process of the lid from one to the other bistable state.

Snap-on closures are characterized in that they can snap in a bistablemanner between an open state and a closed state. They generally consistof a disc-shaped top wall which is deformable in a bistable mannerbetween a concave first state and a convex second state, and an annularedge portion. The outer periphery of the annular edge portion decreasesupon transition of the top wall from the first state to the secondstate.

Such snap-on closures used to be made of metal only and were marketed byHoffmann Neopac as merchandising products under the brands Klick-Klack®and Klipp-Klapp®. In patent documents DE 10 2015 103 036 B4 and WO2017/076398 A1 it is described how such snap-on closures can now also bemade of plastics. The most important aspect for the functioning of thesnap mechanism is the transfer of the bistable deformation of the topwall to the adjacent annular edge portion. Only if the flipping-overmovement between the convex and the concave curvature of the top walltransfers its deformation stress to the edge portion, this allows for awidening of the edge portion and a corresponding enlargement of theouter circumference of the closure cap, which then also allows foropening the container covered by the cap. Here it is of centralimportance that the angle included at the transition between the topwall and the edge portion remains the same for both bistable states,i.e. that the closure cap material at this transition region is stiffenough to transfer the deformation stress of the top wall completely tothe edge portion.

In addition, the edge portion itself should be sufficiently flexible toallow its outer periphery to widen in the first bistable state of thetop wall which is curved in the direction of attachment. According to DE10 2015 103 036 B4, this is achieved, for example, by the fact thatfolds are formed at the edge portion which unfold in the first state andthus allow the outer circumference to be enlarged. Then the entire covercan be made of a single plastic material with homogeneous density orelasticity. Preferably, however, the edge portion obtains the necessaryelasticity by forming at least one expansion portion in the edge portionof the cover from a softer material component than the remaining edgeportion (see WO 2017/076398 A1). The expansion portion expandselastically under stress and allows the edge portion to expand into aconcave curvature state, while the base material of the cover isotherwise stiff enough to maintain a constant angle in the transitionregion between the top wall and the edge portion. This allows the coverto be folded over into the bistable state with the larger outercircumference.

The expansion portion is preferably manufactured in one piece togetherwith the rest of the cover using a multi-component injection moldingprocess. A second material component is injected for the expansionportion. The second material component is softer and/or more elasticthan the first material component used for the rest of the cover. Inorder to further support the constant angle in the transition regionbetween the top wall and the edge portion, the cover in this transitionregion may also preferably have a higher material thickness of theharder (base) material component than in the main region of the top wallor be injected by use of an even harder third material component. Thisyields the particular advantage that the overall thickness of the covermaterial may remain constant. A homogeneous thickness is not onlyvisually appealing, but also reduces the number of steps and edges inwhich dirt can accumulate.

A design in which a latching ring made of the softer second materialcomponent is molded onto the entire inner and/or outer circumference ofthe edge portion is particularly preferred. This latching ring can seala groove or a step in the side wall of the opening to be closed, so thateven a sealing closure of the opening is possible.

There is still room for improvement in the presently available plasticsnap-on closures with regard to the user's operation of theflipping-over process. Until now, it has been mandatory to press or pullup the cover with a certain minimum force at its edge portion or at ahandle member formed on its top wall in order to allow the top wall tosnap from one bistable state to the other. This has the disadvantagethat the areas on which the user is to exert his force must always besufficiently exposed in order to reach the desired pressure points withthe fingers. This, in turn, undesirably restricts the designpossibilities for the overall closure system consisting of container andcover. On the other hand, it would be desirable to reduce the minimumforce required for the snap-action process if the user applies the forceat precisely predefined pressure points. It would also be advantageousif none of the snap-action states would be exclusively operable by apulling force, because then there would no longer be any necessity toprovide a (two-hand-operated) handle member on the cover.

Accordingly, the object of the present invention is to provide, in aclosure system consisting of a three-dimensional structure with theopening to be closed and a cover which snaps between two states in abistable manner, more possibilities for the user to trigger thesnap-over process and, preferably, to reduce the minimum force requiredfor the triggering operation. In particular, a closure system isdesirable in which both bistable states can be triggered by manualpressing, so that both snap-open processes can be operated without ahandle member and usually with just one hand.

At least a partial solution to the above-mentioned problem is achievedby the features of present claim 1. The subclaims relate to preferredembodiments.

In accordance with the present invention, the three-dimensionalstructure, in particular a container or a tubing end which is open on atleast one side, is configured in such a way that a force acting on theclosure system from outside at at least one predefined location istransferred to the edge portion of the cover in such a way that thecover is snapped from one bistable state to the other.

In the case of a lid clamping from inside against an opening wall, theopening wall of the three-dimensional structure is preferably flexibleat least at the predefined location in such a way that, by elasticdeformation, a force acting on the opening wall at least on one side,and preferably on both sides, transversely to the direction ofattachment is transmitted to the edge portion of the lid. This allowsthe lid to lie completely within the opening to be closed without theneed for the user to provide a handle member on the top wall of the lidto trigger the snap-over process into the open position. In aparticularly preferable embodiment, the point of the opening wall whichis, opposite to the direction of attachment, most remote projects by acertain amount of projection from the location at which the edge portionof the lid presses from the inside against the wall region. A forceacting transversely to the direction of attachment on this outer wallregion can then trigger the snapping-over of the cover with less effort,because the protrusion acts as a lever arm.

According to another preferred embodiment, the cover clamps as a capfrom the outside around the wall region of the opening to be closed. Thegeometric design of the wall region of the opening at the outermost endregion in the direction opposite to the direction of attachment allowsthe cap to contact this end region with an area of the top wall that isa little offset from the edge portion towards the center of the cap.This allows the cap to be brought into its closed position not only by aforce acting transversely to the direction of attachment on the edgeportion, but also by a force exerted in the direction of attachment,provided that this force is exerted on a pressure point which isradially further outwards than the contact point of the opening wallwith the top wall. The distance between the contact-point and thepressure-point here again works as lever arm and reduces the requiredoperating force correspondingly.

In this description, the closure element of the opening to be closed isgenerally referred to as a cover. If the cover clamps on the outside ofthe opening wall, the cover is called a cap; if the cover clamps on theinside against the opening wall, it is called a lid.

In the following, the invention is explained in greater detail usingseveral embodiments. Therein shows:

FIG. 1a a side view of a closure cap partially shown in sectionaccording to a first embodiment of the invention;

FIG. 1b a top view of the cap of FIG. 1 a;

FIG. 1c an enlarged detailed view in a section A-A in FIG. 1 a;

FIG. 1d an enlarged view of a detail X of FIG. 1 a;

FIG. 1e an enlarged detailed view in a section C-C in FIG. 1 c;

FIG. 1f an enlarged detailed view in a section B-B in FIG. 1c , in whichat the same time the closure principle of a container with the cap isshown;

FIG. 2a a cross-sectional view of a closure system of the presentinvention with the closure cap according to the first embodiment in theopen position;

FIG. 2b a cross-sectional view of the closure system of FIG. 2a in theclosed position;

FIG. 2c an enlarged detail of FIG. 2a in a first modification of thefirst embodiment in the open position;

FIG. 2d the enlarged detail of FIG. 2a in a second modification of thefirst embodiment in the open position;

FIG. 2e the enlarged detail of FIG. 2a in a third modification of thefirst embodiment in the open position;

FIG. 3a a cross-sectional view of a closure system of the presentinvention with a closure lid according to a second embodiment in theopen position;

FIG. 3b a cross-sectional view of the closure system of FIG. 3a in theclosed position;

FIG. 3c an enlarged detail of FIG. 3 b;

FIG. 3d the enlarged detail of FIG. 3c in a first modification of thesecond embodiment in the closed position;

FIG. 3e the enlarged detail of FIG. 3c in a second modification of thesecond embodiment in the closed position; and

FIG. 3f the enlarged detail of FIG. 3c in a third modification of thesecond embodiment in the closed position.

In the first embodiment shown in FIGS. 1a-f , the cover is designed as acap 20, which is to embrace a container wall 12 a from the outside. TheFIGS. 1a to 1f all show the cap 20 in its convex and outwardly curvedsnap position (i.e. curved in the direction opposite to the direction ofattachment). This is the shape the cap takes in its locking position.FIG. 1f also shows how it is possible to snap into the opening wall 12 ato be closed in this position, but this will be explained in greaterdetail later referring to FIGS. 2a to 2 e.

The cap 20 shown in FIGS. 1a-f has a top wall 21 which is essentiallycircular in shape, with a ring-shaped edge portion 22 formed on itsouter periphery. FIG. 1a shows a side view partially shown in section.In the left part of the Figure the cap 20 can be seen from the side,while the right part is cut inside so that the back inside of the cap 20can be seen. In the Figures, the uncut soft component (second materialcomponent) is always dotted and the cut soft component is crosshatched,while the cut hard component (first material component) is simplyhatched.

If the top wall 21 snaps into its concave and downwardly (i.e. in thedirection of attachment) curved state, the outer circumference of theedge portion 22 increases. In order to keep the angle μ, which isincluded by the top wall 21 and the edge portion 22 in their transitionregion, constant in the two bistable states, the cap material shouldhave sufficient rigidity. According to the invention, this is achievedby the fact that the transition region between the top wall 21 and theedge portion 22 has, at least in partial regions, but preferably overthe entire circumference, a higher material thickness than the centralregion of the top wall 21. As shown in FIGS. 1e and 1f , the materialgets thicker upwards, i.e. in the direction opposite to the direction ofattachment, so that the transition region between the top wall 21 andthe edge portion 22 runs smoothly on the inside. Alternatively, thematerial thickenings can also extend downwards and lead to acorrespondingly contoured inner wall surface of the lid.

The outer circumference in the concave bistable state (explained lateron referring to FIG. 2a ) is enlarged as compared to the convex stateshown in FIGS. 1e, 1f and 2b . This enlargement requires a sufficientstretching flexibility of the circumferential edge portion 22 to enablethe increased outer circumference in the concave bistable state.According to the present invention, this is achieved bycircumferentially (preferably equidistantly) arranged expansion portions24 made of the softer second material component, which alternate—as canbe seen particularly well in FIGS. 1a and 1d —with intermediate portions23 made of the harder first material component. As shown in FIG. 1b ,the expansion portions 24 start from the transition region between topwall 21 and edge portion 22 and then widen towards the radial outeredge. The softer material of the expansion portions 24 ensures that theedge portion 22 can enlarge at its outer circumference when being in theconcave (i.e. open) snapping position of the cap 20. The expansionportions 24 would then no longer have the constant width shown in FIGS.1a and 1 d, but would widen radially outwards.

The edge portion 22 terminates in its expansion portions 24 as well asin its intermediate portions 23 in a latching ring 29 which is providedat the inner circumference and which is also formed from a softermaterial component, preferably the same as the expansion portions 24.This inner circumferential latching ring 29 imparts additionaldimensional stability to the thin-walled cap 20, but is alsosufficiently elastic to enable the enlargement of the outercircumference in the convex foldover position shown in FIG. 2a . Due toits softer material properties, the latching ring 29 can work as asealing ring.

The latching ring 29 is formed on a lip portion 23 a, 24 a of the edgeportion 22, the lip portion projecting radially inwards by 90°. Thereason for this is that the cap 20 should grip the opening 11 a to beclosed from the outside, as will be explained in greater detail in FIG.1f and, in particular, in FIGS. 2a-e . The lip portion 24 a adjacent tothe expansion portion 24 is made of the softer second materialcomponent, while the lip portion 23 a adjacent to the intermediateportion 23 is made of the harder first material component. However, thelip portions 23 a and 24 a can also be entirely formed from the softersecond material component. In this case, the entire radial inner part ofthe edge portion 22 would belong to the latching ring 29 or the lipportion would be omitted.

As a manufacturing process for the cap 20, the above-mentionedmulti-component injection molding using one or more thermoplastics isparticularly suitable. The multi-component technique allows a first(base) component to be injected for the top wall 21 and the intermediateportions 23, while the expansion portions 24, as well as the latchingring 29, are directly injected from a softer second component in asingle manufacturing process. The optional third (particularly hard)material component for the transition region between the top wall andthe edge portion can also be injection-molded directly in a singlemulticomponent injection molding process.

Preferred materials for the first component are: thermoplasticelastomers (TPE) and thermoplastic urethane (TPU).

Preferred materials for the second component are: Polycarbonate (PC),Acrylonitrile Butadiene Styrene (ABS) and Polystyrene (PS).

Preferred materials for the third component are: glass fiber reinforcedpolyamide (PA) or other glass fiber reinforced plastics.

Instead of producing the cover entirely by injection molding, it is alsopossible to overmold a blank obtained previously in a separatemanufacturing step. It is conceivable, for example, that a cap which ismade of sheet metal or a light metal (e.g. aluminum) and whichessentially has the shape of a conventional Klick-Klack box cap withmetal fingers at the outer periphery, could be encapsulated in the edgearea with the softer (second) plastic component. The obtained result isa cover with significantly improved tightness against the leakage ofliquids or gases from the box to be closed.

Instead of manufacturing the cap or lid from several material componentsof different hardness or elasticity, the cap or lid can also bemanufactured by a thermoforming process, i.e. deep drawing, or by aninjection molding process from only a single plastic material. Then,instead of the softer expansion portions at the edge portion, theabove-mentioned folds are formed and reinforcement ribs and/or materialthickenings are provided at the transition region between the top walland the edge portion to keep the inner angle there constant in bothbistable states.

FIGS. 2a-e show the functional principle of the cap 20 according to thefirst embodiment of the invention in a closure system consisting of thecontainer 10 a and the cap 20. The opening 11 a to be closed has, in theshown wall region 12 a, a circular groove 13 a on the outer surface, atthe lower end of which a step 15 a is formed. The step is not necessaryand can also be omitted. Above the groove 13 a, the wall region 12 acontinues into a protrusion 14 a, which has essentially the same heightas the edge portion 22 of the cap 20.

FIG. 2a shows the cap 20 in its open, concave position, i.e. with thetop wall 21 curved downwards. The inner diameter of the edge portion 22is correspondingly larger. This inner diameter is larger than the outerdiameter of the outer groove 13 a, so that the cap 20 can be removedfrom the opening 11 a in the open state shown in FIG. 2 a.

In FIG. 2b , the top wall 21 has a convex curvature, i.e. it is curvedupwards in the direction opposite to the direction of attachment. Then,the edge portion 22 with the inwardly projecting latching ring 29 onlyhas an inner diameter which is smaller than the outer diameter of thegroove 13 a. Thus, the cap 20 is firmly engaged with the opening wall 12a to be closed and only snaps back into its first bistable state shownin FIG. 2a when a force F acts on the top wall 21 in the direction ofattachment. Due to its elastic material properties, the ring 29 alsoworks as a sealing ring to prevent gases or liquids from escapingthrough the opening 11 a.

As can be seen particularly well in FIG. 2c , the end section 16 of thewall region 12 a is tapered, i.e. the outer diameter of the opening 11 anarrows in this end section 16, while the inner diameter of opening 11 aremains constant. This provides a contact point A1 between the top wall21 and the end section 16 which is offset towards the center of thecover 20 by a distance a1 from the transition region between the topwall 21 and the edge portion 22. If a force F₂, which acts essentiallyin the direction of attachment, is exerted from above on the top wall 21at a pressure point A2, this force F₂ acts on the edge portion 22 via alever arm of the length a1 and triggers the snap-over process. Untilnow, this was only possible by means of the force F₀ acting directly onthe edge portion 22 in FIGS. 2a, 2c and 2d from sideward, essentiallytransversely to the direction of attachment.

As also shown in FIG. 2c , an additional extension 18 may be attached ormolded to edge portion 22 in accordance with an optional modification.This extension 18 makes it possible to reduce the force F₀, actingessentially transversely to the direction of attachment and required toclose the cap, to a lower value F₁, because the user can exert his forcevia an extended lever arm when he compresses the cap 20 at the extension18.

According to another modification shown in FIG. 2d , the lever arm a1can be extended by providing a narrowing element 17 to the end section16′, which narrowing element can be attached to or integrally formed atthe end section 16′ and which also constricts the inner diameter of thewall region 12 a, i.e. the opening 11 a, in the area of the end section.Then a force F₃ exerted on the pressure point A2 acts via the longerlever arm a2 with the contact point A1 as a lever point even moreefficiently on the edge portion 22 and thus facilitates the release ofthe snapping-over process.

According to another modification shown in FIG. 2e , the lever arm a1 ofFIG. 2c can also be extended by a top wall extension 19. In contrast tothe extension 18 shown in FIG. 2c , the top wall extension 19 is notarranged at the edge portion 22 but at the top wall 21. This top wallextension 19 can be attached to or integrally molded with the top wall21, in partial areas or across the entire circumference thereof. The topwall extension allows the force F₂, which acts essentially in thedirection of attachment and which is required to close the cap 20, to bereduced to a lower value F₃′. When the user presses the cap 20 down at apressure point A2 of the extension 19, an applied force F₃′ generates,due to the longer lever arm a2′ with contact point A1 as the leverpoint, a greater torque than that generated by the force F₂ via thelever arm a1 of FIG. 2c . Otherwise, the structure according to themodification shown in FIG. 2e corresponds to that of FIG. 2c . It goeswithout saying that the modifications shown in FIGS. 2c, 2d and/or 2 ecan also be used in combination.

FIGS. 3a to 3f show the functioning of another closure system accordingto the present invention. The system uses a lid 30 according to thesecond embodiment to close an opening 11 a. The lid can be manufacturedin the same way as previously described for the cap 20 and has expansionportions and intermediate portions in the edge portion 32 in the sameway, whereby only the intermediate portions 33 are visible in thecross-sections of the Figures for the sake of clarity. Also, the lipportions and the modifications are possible with the lid 30 analogouslyto the cap 20.

The only difference to cap 20 is that the lid 30 does not have aninwardly protruding latching ring 29, but an outwardly protrudinglatching ring 39. This is because it is not intended to clamp to thecontainer wall from the outside, but from the inside. Anotherconceivable option is, of course, a cover with both an inwardly and anoutwardly projecting latching ring, which can then be used as both a capand a cover. Furthermore, it would also be possible to place the lid 30upside down on the box 10 b without significantly changing itsfunctionality. The middle section of the edge portion 32 would then notextend in the direction of attachment but also opposite thereto, and thecover 30 would change from its closed state to its open state byexerting a pressure on the top wall 31 in the direction of attachment,which can be advantageous for certain applications.

The edge portion 32 thus ends both in its expansion portions (not shown)and in its intermediate portions 33 in an outer circumferential latchingring 39. The latching ring is also formed from a softer materialcomponent, preferably the same material as the expansion portions. Thiscircumferential latching ring 39 not only gives the thin-walled lid 30additional dimensional stability, but is also sufficiently elastic toenable the enlargement of the outer circumference in the convex foldingposition shown in FIG. 3b . Due to its softer material composition, thelatching ring 39 not only clamps particularly well in the inner groove13 b of the opening wall 12 b to be closed, but can also provide thefunctionality of a sealing ring.

The wall region 12 b of the opening 11 a to be closed has a ring-shapedgroove 13 b inside, into which the lid 30 is to engage, and which formsa step-shaped shoulder 15 b at its lower edge. The area of the wallregion 12 b above the groove 13 b (i.e. against the direction ofattachment) is referred to as the protrusion 14 b.

If the lid 30 is inserted from above into the opening 11 b, the edgeportion 32 hits with its latching ring 39 against the step 15 b. Thistells the user that the axial end position of the cover 30 has beenreached which is the end position intended for locking. If the user nowpresses the top wall 31 downwards by a force F acting verticallydownwards, the top wall 31 snaps from its convex bistable state shown inFIG. 3a into its concave bistable state shown in FIG. 3b . Due to thestiffness of the cover material in the transition region between topwall 31 and edge portion 32, which (as explained above) is preferablysupported by an increased material thickness, the angle μ remainsconstant during this snap-over process, so that the edge portion 32folds slightly outwards to the side and causes the latching ring 39 tosnap into the groove 13 b. In the concave top wall position of FIG. 3b ,the latching ring 39 presses laterally from the inside into the annulargroove 13 b of the opening wall 12 b and thus locks the lid 30 into itsclosed position. The material is stretched in the expansion portions 34into a—when seen in a plan view—widened state and the outer diameter ofthe edge portion 32 increases during this folding process. FIG. 3c showsin detail the engagement of the ring 39 into the groove 13 b.

To uncover the opening 11 b again, the lid 30 must snap back into itsoriginal state. It can then be pulled out of the opening 11 b due to itsreduced outer diameter. Conventionally, a handle member on the top wall31 was provided for this purpose. By the handle member, the lid 30 couldbe seized and pulled upwards. As described in detail below, the secondembodiment of the present invention also allows the lid to be openedwith a force F₄, F₅ acting laterally (transversely to the direction ofattachment) on the container wall 12 b, so that the handle member can bedispensed with.

As can be seen best in the enlarged representation of FIG. 3c , theprotrusion 14 b has a length b1 up to the outermost (opposite to thedirection of attachment) end of the wall region 12 b. If the user nowexerts, transversely to the direction of attachment, from the outside atthe pressure point B2 a force F₄ on the wall region 12 b, this force,with the length b1 acting as a lever arm and with the contact point B1between wall region 12 b and edge portion 32, acts by the elasticdeformation of the protrusion 14 b in such a way on the cover 30 thatthe cover 30 can snap into the open state without the need for anydirect pressing of the edge portion 32 or pulling of the top wall 31 viaa handle member or the like.

As shown in FIG. 3d , the protrusion 14 b′ can also be longer accordingto a first modification of the second embodiment. This not only extendsthe lever arm to the length b2 and reduces the force F₅ required to openthe cover 30, but the cover 30 is then also completely protected insidethe opening 11 b, which makes any unintentional opening of the closuresystem more unlikely.

FIG. 3e shows a second modification of the second embodiment. Here, thewall region 12 b below the inner groove 13 b has an opening in which aslider 13 c is mounted. The slider 13 c is a rod-shaped actuatingelement for opening the cover 30 and can be displaced in the openingtransversely to the direction of attachment. For this purpose, the userexerts a force F₅′ on the actuator 13 d mounted to or integrally formedwith the outer end of the slider 13 c from outside transversely to thedirection of attachment. In the modification of the embodiment shown,the actuator 13 d has the shape of a hemispherical actuating knob.

The other end of the slider 13 c meets the end of an edge portionextension 34 protruding in the direction of attachment from the edgeportion 32 inside the container 10 b. The extension 34 can be attachedto or integrally formed with the edge portion 32 in partial areas orover the entire circumference. In the modification shown, the extensionessentially has a length b3 and is thus longer than the edge portion 32as such. The extension 34 acts as a lever arm of the length b3 up to thetransition region between edge portion 32 and top wall 31.

If the slider 13 c is pushed inwards with the minimum force F₅′ at theactuator 13 d, the extension 34 is moved such far into the interior ofthe container that it transfers, to the top wall 31 via the lever armb3, the torque necessary for switching into the open bistable state. Thesame force F₅′ when acting on the remaining wall region 12 b would notbe sufficient for opening of the cover 30—for example, because the wallthickness or strength of the container wall is large enough to makeforce transmission to the edge portion extension 34 sufficientlydifficult. This additionally increases safety against any unintentionalopening of the box-lid system.

As shown in the third modification of the second embodiment in FIG. 3f ,the slider 13 c and the actuator 13 d can also be omitted. Instead, thewall region 12 b may have a constriction 13 e where the wall thicknessis weakened. The constriction 13 e can be provided as a circumferentialring-shaped recess or only as a grasping recess arranged in partialareas, preferably at two diametrically opposed points. If the minimumforce F₅″ is used to press the wall region at the area of theconstriction 13 e radially inwards, the extension 34 deforms towards theinside of the container to such an extent that it transfers the torquerequired to switch the top wall 31 via the lever arm b3 into the openbistable state. Apart from the wall thickness weakened by theconstriction 13 e, the container wall 12 b is strong enough to preventunintentional opening with the force F₅″. This avoids any impairing ofthe container tightness which may arise in the second modification withthe wall opening and the slide 13 c. On the other hand, for certainapplications such wall breakthroughs are desirable, e.g. for pressureequalization between the container inside and ambient pressure. Insteadof the constriction 13 e, the wall region 12 b can also be softened atthis location in another way, for example by using a softer materialcomponent or subsequently softening the wall region 12 b at thislocation.

In summary, the present invention relates to a closure system with athree-dimensional structure 10 a, 10 b, in particular a container or anopening region of a technical apparatus, and a cover 20, 30 for fittingonto the three-dimensional structure 10 a, 10 b in order to close itsopening 11 a, 11 b. The cover 20, 30 has a top wall 21, 31 which isdeformable in a bistable manner between a first state curved in thedirection of attachment and a second state curved opposite to thedirection of attachment, and an annular edge portion 22, 32. The edgeportion has a larger outer circumference in the first bistable statethan in the second bistable state and is therefore adapted to effect aclamping attachment of the cover 20, 30 to a wall region 12 a, 12 b ofthe opening 11 a, 11 b by the edge portion 22, 32 pressing against thewall region 12 a, 12 b in the first state from inside or pressingagainst the wall region 12 a, 12 b in the second state from outside. Thethree-dimensional structure 10 a, 10 b is configured to transfer a forceexerted on the closure system at predefined locations A2, B2 from theoutside in such a way that it leads to a snapping of the cover 20, 30from one to the other of the two bistable states.

LIST OF REFERENCE SIGNS

-   -   10 a, 10 b container    -   11 a, 11 b opening    -   12 a, 12 b sidewall    -   13 a outer groove    -   13 b inner groove    -   13 c wall penetration with slider    -   13 d actuator    -   13 e constriction    -   14 a, 14 b, 14 b′ protrusion    -   15 a, 15 b step    -   16, 16′ end section    -   17 narrowing element    -   18 extension of edge portion of cap    -   19 extension of top wall    -   20, 30 cover    -   20 cap    -   30 lid    -   21, 31 top wall    -   22, 32 edge portion    -   23, 33 intermediate portions (hard)    -   24 expansion portions (soft)    -   23 a lip portion inside (hard)    -   24 a lip portion inside (soft)    -   29 inner latching ring (soft)    -   33 a lip portion outside (hard)    -   34 extension of edge portion of cover    -   39 outer latching ring (soft)    -   a1, b1, a2, a2′, b2, b3 lever arms    -   A1, B1 contact point    -   A2, B2 pressure point

1-20. (canceled)
 21. A closure system, comprising: a three-dimensionalstructure having an opening to be closed; and a cover for attachmentonto said three-dimensional structure to close said opening, said covercomprising: a top wall that is deformable in a bistable manner between afirst bistable state which is cambered in a direction of attachment anda second bistable state which is cambered opposite to the direction ofattachment; and an annular edge portion having an outer circumferencethat is greater in the first bistable state than in the second bistablestate and being configured to effect a clamping attachment of said coverto a wall region of said opening by pressing said edge portion in thefirst state from inside or in said second state from outside againstsaid wall region; and said three-dimensional structure being configuredto transfer a force exerted on the closure system from outside at atleast one predefined location to cause said cover to snap from one ofthe two bistable states to another of the two bistable states.
 22. Theclosure system according to claim 21, wherein: in a closed state of theclosure system, the edge portion of said cover presses in the firststate at a contact point from inside against said wall region; and saidthree-dimensional structure, at least at the at least one predefinedlocation, is formed of a material which is so flexible that a forceacting transversely to the direction of attachment on said wall regionof said opening from at least one outer side or from two opposite outersides causes said cover to snap from the first bistable state to thesecond bistable state.
 23. The closure system according to claim 22,wherein: said wall region has at least one narrowing point at which asize of said opening decreases; and the size of said cover isdimensioned such that, in the open state of the closure system, saidcover fits into said opening only up to the narrowing point thereof andrests with the edge portion against the narrowing point.
 24. The closuresystem according to claim 23 wherein, in order to open the closuresystem: a force acting transversely to the direction of attachment fromtwo opposite outer sides acts on the wall region of said opening at apressure point which is spaced from a narrowing point in the directionopposite to the direction of attachment; and the force acts via a leverarm formed by a distance between the pressure point and the contactpoint on the edge portion abutting at the narrowing point and causessaid cover to snap from the first bistable state into the secondbistable state.
 25. The closure system according to claim 23, whereinthe wall region is formed with a groove, which is spaced from thenarrowing point in the direction opposite to the direction of attachmentand which is configured to engage with a clamping element of the edgeportion of said cover.
 26. The closure system according to claim 21,wherein: an extension in the direction of attachment is attached to orintegrally formed with the edge portion and extends, in the closed stateof the cover in the direction of attachment, at least up to thepredefined location of the three-dimensional structure, and transfers aforce acting from two opposite outer sides of the wall region to the topwall in such a manner that the top wall snaps from the first bistablestate to the second bistable state; and the wall region has apenetration at the predefined location with a sliding element whichextends transversely to the direction of attachment and is movabletransversely to the direction of attachment on account of the forceacting from the at least one opposite outer side of the wall region sothat it is being pressed against the extension in order to open thecover.
 27. The closure system according to claim 21, wherein: in aclosed state of the closure system, the edge portion of the coverpresses in the second state at a contact point from outside against thewall region; and the wall region at an outermost end portion thereof,when seen opposite to the direction of attachment, is shaped such that asnap-over of said cover from the first bistable state to the secondbistable state and thus a closing of the closure system cannot only beeffected by a force acting transversely to the direction of attachmentfrom two opposite sides on the edge portion of the cover but also by aforce acting in the direction of attachment on a predefined location ofthe top wall.
 28. The closure system according to claim 27, wherein: theoutermost end portion of said opening wall is shaped such that, in theopen state of the closure system, the top wall of the cover contacts theopening wall at a contact point which is closer to the center of theopening than the transition region between the top wall and the edgeportion; and a force acting on the region of the top wall of said coverin the direction of attachment at a pressure point acts on the edgeportion via a lever arm formed between the pressure point and thecontact point and causes said cover to snap over from the first bistablestate to the second bistable state.
 29. The closure system according toclaim 28, wherein the outermost end portion of the opening wall has ashape which tapers transversely to the direction of attachment.
 30. Theclosure system according to claim 28, wherein the opening narrows at theoutermost end portion of the opening wall.
 31. The closure systemaccording to claim 28, further comprising: an extension extendingsubstantially in the direction of attachment mounted or integrallyformed at the edge portion and extending the lever arm of the force,said force acting transversely to the direction of attachment from atleast one and preferably from two opposite outer sides on the edgeportion for closing the closure system; and/or an extension extendingsubstantially transversely to the direction of attachment attached orintegrally formed at the top wall and extending the lever arm of theforce, said force acting in the direction of attachment on thepredefined location for closing the closure system.
 32. The closuresystem according to claim 21, wherein said three-dimensional structureis a container.
 33. The closure system according to claim 21, whereinthe edge portion of said cover comprises at least one expansion portionformed of a second material component which is softer than a harderfirst material component forming a remaining edge portion and allowing awidening of the outer periphery of the edge portion in the firstbistable state relative to the second bistable state.
 34. The closuresystem according to claim 33, wherein said cover is integrally made ofplastics by a multi-component injection molding process.
 35. The closuresystem according to claim 33, wherein the edge portion of said covercomprises a plurality of expansion portions of the softer secondmaterial component which, starting from a transition region between theedge portion and the top wall, alternate equidistantly with intermediateportions of the harder first material component of the remaining edgeportion.
 36. The closure system according to claim 21, wherein the topwall merges into the edge portion with a constant angle that remains thesame in the first bistable state and in the second bistable state. 37.The closure system according to claim 21, wherein a material thicknessat a transition from the top wall to the edge portion is at least inpartial regions greater than in a remaining region of said cover. 38.The closure system according to claim 21, wherein said cover, at atransition from the top wall to the edge portion, is formed, at least inpartial regions thereof, from a material component that is harder than amaterial component forming a remaining said top wall and an entire saidcover has a substantially uniform material thickness.
 39. The closuresystem according to claim 33, wherein the edge portion in and outsidethe region with the expansion portion has a central portion extendingaxially in the direction of attachment or opposite thereto, and a lipportion adjacent to the central portion and extending radially inwardsand/or outwards.
 40. The closure system according to claim 33, furthercomprising a latching ring integrally formed at an end region of theedge portion or the lip portion, said latching ring being formed of amaterial which is softer or more elastic than the first materialcomponent.